A double-winder turns 180° using two sets of pie-shaped winder treads instead of a landing. Check narrow-end and walking-line depths to code.
A double-winder reverses direction through 180 degrees entirely on winder treads — two winder sets rather than the single 90° turn of a standard winder stair.
A staircase that turns 180 degrees using two sets of pie-shaped winder treads instead of landings.
Yes. With more pie treads across a tighter turn, the narrow ends are more likely to fall below minimum depth.
Commonly five to seven across a 180° turn, depending on inner radius and code.